There are some exotic foods we tend to take for granted exist. Almost every city for example has a Chinese restaurant, a Mexican restaurant, and maybe an Outback Steakhouse. But this isn't universal for some reason. Someone asked me if I wanted to go to an Egyptian restaurant and I was like "wait, they have restaurants?"
A question for all those who would say they consider themselves ethnically fluent. What are all the cultural categories of food you've had?
You can't live on breast milk either, plus it would lead to abnormal growth and you'd need to alternate between women as we don't have an infinite supply of breast milk in our bodies.